本論文提出了一個使用截波穩定技術(Chopper Stabilization Technique)的互補式金氧半導體飛時測距型深度影像感測器，具有偏移誤差(Offset)消除及閃爍雜訊(Flicker Noise)壓抑的能力。
為了解決飛時測距型深度影像感測器的像素(Pixel)內背景光飽和的問題，我們在考慮了像素內背景光消除的能力以及像素面積之後，選擇了一個使用感光二極體(photodiode)做極性轉換積分的架構。然而，此架構會有偏移誤差累加的問題，偏移誤差累加的量甚至比背景光的積分還要更嚴重，除此之外，還有閃爍雜訊累加的問題，會使距離量測的準確度大幅下降。因此，我們採用了截波穩定技術，考慮了P+/N-well接面的感光二極體與N-well/P-sub接面的寄生感光二極體之後，我們將截波穩定的頻率設定在調變頻率(Modulation Frequency)的二分之一，如此一來，不論是感光二極體或是寄生感光二極體所造成的偏移誤差的累加以及閃爍雜訊的累加都可以被消除。此外，為了達到更好的距離準確度，我們也提升了調變頻率。
此架構使用TSMC 0.18微米1P6M互補式金氧半導體標準製程檔進行模擬，設計並模擬驗證一個擁有64×64像素陣列的飛時測距型深度影像感測器原型，類比端的操作電壓為3.3伏特，數位端為1.8伏特。影像感測器的像素間距(Pixel Pitch)為22微米，填充因子(Fill Factor)為26%。模擬結果顯示，在距離範圍為0.45到2.1公尺達到99%線性度，並且可將1公尺下的準確度提升10倍。

This thesis presents a CMOS time-of-flight (TOF) depth image sensor with in-pixel offset cancellation and flicker noise suppression by adopting chopper stabilization technique.
To deal with in-pixel background light saturation issue in TOF depth image sensors, a TOF pixel with photodiode polarity switching integration technique is chosen for its great performance in in-pixel background light cancellation and relatively small pixel area by using only one integration capacitor. However, this TOF pixel structure suffers from offset accumulation even more critical than the original background light issue, and the low frequency flicker noise accumulation degrades the accuracy. Therefore, chopper stabilization technique is implemented. After taking both P+/N-well photodiode and N-well/P-sub parasitic photodiode into consideration, with chopper stabilization performed at half of the modulation frequency, both offset accumulation and low frequency flicker noise accumulation induced by photodiode and parasitic photodiode are eliminated. Moreover, for better accuracy performance, the modulation frequency is increased.
A prototype of 64×64 pixel array TOF depth image sensor has been designed and simulated in TSMC standard 0.18μm 1P6M CMOS technology with 3.3V supply voltage for analog and 1.8V for digital. The pixel pitch is 22μm with a fill-factor of 26%. The simulation results show that the proposed chopper stabilized TOF depth sensor achieves 99% linearity within a range of 0.45 to 2.1 meters, and the accuracy at 1 meter achieved a 10 times improvement.

[1] V. Ganapathi, C. Plagemann, D. Koller, and S. Thrun, “Real Time Motion Capture Using a Single Time-of-Flight Camera,” IEEE Computer Society Conference on Computer Vision and Pattern Recognition, 2010.
[2] M. Van den Bergh and L. Van Gool, “Combining RGB and ToF Cameras for Real-Time 3D Hand Gesture Interaction,” IEEE Workshop on Applications of Computer Vision, 2011.
[3] P. J. Besl, “Active, Optical Range Imaging Sensors,” Machine Vision and Applications, vol. 1, pp. 127-152, 1988.
[4] R. G. Dorsch, G. Hausler, and J. M. Herrmann, “Laser Triangulation: Fundamental Uncertainty in Distance Measurement,” Applied Optics, vol. 33, pp. 1306-1314, 1994.
[5] J. Ohta, “Smart CMOS Image Sensors and Applications,” CRC Press, 2007
[6] J. Nakamura, “Image Sensors and Signal Processing for Digital Still Cameras,” CRC Press, 2005
[7] L. Yao, “CMOS Readout Circuit Design for Infrared Image Sensors,” proceedings of the SPIE, International Symposium on Photoelectronic Detection and Imaging, vol. 7384, 2009.
[8] A. W. Hoffman, “Capacitor Transimpedance Amplifier ( CTIA) with Shared Load,” US patent 6,252,462, 2001.
[9] R. Lange, “3D Time-of-Flight Distance Measurement with Custom Solid-State Image Sensors in CMOS/CCD-Technology,” 2000.
[10] M. Abdelhamid, J. Beers, and M. Omar, “Extracting Depth Information Using a Correlation Matching Algorithm,” Journal of Software Engineering and Applications, vol. 5, 2012.
[11] S. Koyama, K. Onozawa, K. Tanaka, and Y. Kato, “A 3D vision 2.1Mpixel image sensor for single-lens camera systems,” IEEE International Solid-State Circuits Conference, Digest of Technical Papers, 2013.
[12] Y. Oike, M. Ikeda, and K. Asada, “A 120×110 Position Sensor With the Capability of Sensitive and Selective Light Detection in Wide Dynamic Range for Robust Active Range Finding,” IEEE Journal of Solid-State Circuits, vol. 39, no. 1, pp. 246-251, 2004.
[13] L. Gasparini, M. Zarghami, H. Xu, L. Parmesan, M. Moreno Garcia, M. Unternährer, B. Bessire, A. Stefanov, D. Stoppa, and M. Perenzoni, “A 32×32-pixel time-resolved single-photon image sensor with 44.64μm pitch and 19.48% fill-factor with on-chip row/frame skipping features reaching 800kHz observation rate for quantum physics applications,” IEEE International Solid-State Circuits Conference, 2018.
[14] C. Niclass, A. Rochas, P.-A. Besse, and E. Charbon, “Design and characterization of a CMOS 3-D image sensor based on single photon avalanche diodes,” IEEE Journal of Solid-State Circuits, vol. 40, no. 9, pp. 1847-1854, 2005.
[15] C. Niclass, C. Favi, T. Kluter, M. Gersbach, and E. Charbon, “A 128×128 Single-Photon Imager with on-Chip Column-Level 10b Time-to-Digital Converter Array Capable of 97ps Resolution,” IEEE International Solid-State Circuits Conference, Digest of Technical Papers, 2008.
[16] C. Niclass, M. Soga, H. Matsubara, M. Ogawa, and M. Kagami, “A 0.18-μm CMOS SoC for a 100-m-Range 10-Frame/s 200×96-Pixel Time-of-Flight Depth Sensor,” IEEE Journal of Solid-State Circuits, vol. 49, no. 1, pp. 315-330, 2014.
[17] A. R. Ximenes, P. Padmanabhan, M.-J. Lee, Y. Yamashita, D. N. Yaung, and E. Charbon, “A 256×256 45/65nm 3D-Stacked SPAD-Based Direct TOF Image Sensor for LiDAR Applications with Optical Polar Modulation for up to 18.6dB Interference Suppression,” IEEE International Solid-State Circuits Conference, 2018.
[18] A. M. Pawlikowska, A. Halimi, R. A. Lamb, and G. S. Buller, “Single-Photon Three-Dimensional Imaging at up to 10 Kilometers Range,” Optics Express, vol. 25, no. 10, pp. 11919-11931, 2017.
[19] D. Stoppa, N. Massari, L. Pancheri, M. Malfatti, M. Perenzoni, and L. Gonzo, “A Range Image Sensor Based on 10-μm Lock-In Pixels in 0.18-μm CMOS Imaging Technology,” IEEE Journal of Solid-State Circuits, vol. 46, no. 1, pp. 248-258, 2011.
[20] S.-M. Han, T. Takasawa, T. Akahori, K. Yasutomi, K. Kagawa, and S. Kawahito, “A 413×240-Pixel Sub-Centimeter Resolution Time-of-Flight CMOS Image Sensor with In-Pixel Background Canceling Using Lateral-Electric-Field Charge Modulators,” IEEE International Solid-State Circuits Conference, Digest of Technical Papers, 2014.
[21] J. Cho, J. Choi, S.-J. Kim, S. Park, J. Shin, J. D. K. Kim, and E. Yoon “A 3-D Camera with Adaptable Background Light Suppression Using Pixel-Binning and Super-Resolution,” IEEE Journal of Solid-State Circuits, vol. 49, no. 10, pp. 2319-2332, 2014.
[22] C. S. Bamji, S. Mehta, B. Thompson, T. Elkhatib, S. Wurster, O. Akkaya, A. Payne, J. Godbaz, M. Fenton, V. Rajasekaran, L. Prather, S. Nagaraja, V. Mogallapu, D. Snow, R. McCauley, M. Mukadam, I. Agi, S. McCarthy, Z. Xu, T. Perry, W. Qian, V.-H. Chan, P. Adepu, G. Ali, M. Ahmed, A. Mukherjee, S. Nayak, D. Gampell, S. Acharya, L. Kordus, and P. O'Connor, “1Mpixel 65nm BSI 320MHz Demodulated TOF Image Sensor with 3.5μm Global Shutter Pixels and Analog Binning,” IEEE International Solid-State Circuits Conference, 2018.
[23] J, Cho, “CMOS Sensors for Time-Resolved Active Imaging,” 2017.
[24] T. Oggier, R. Kaufmann, M. Lehmann, B. Büttgen, S. Neukom, M. Richter, M. Schweizer, P. Metzler, F. Lustenberger, and N. Blanc, “Novel Pixel Architecture with Inherent Background Suppression for 3D Time-of-Flight Imaging,” Proceedings SPIE, vol. 5665, pp.1-8, 2005.
[25] M. Lehmann, T. Oggier, B. Büttgen, Chr. Gimkiewicz, M. Schweizer, R. Kaufmann, F. Lustenberger, and N. Blanc, “Smart Pixels for Future 3D-TOF Sensors,” IEEE Workshop on CCDs and Advanced Image Sensors, 2005.
[26] B. Büttgen, T. Oggier, M. Lehmann, R. Kaufmann, S. Neukom, M. Richter, M. Schweizer, D. Beyeler, R. Cook, C. Gimkiewicz, C. Urban, P. Metzler, P. Seitz, and F. Lustenberger, “High-Speed and High-Sensitive Demodulation Pixel for 3D Imaging,” Proceedings SPIE, vol. 6056, pp.22-33, 2006.
[27] B. Büttgen and P. Seitz, “Robust Optical Time-of-Flight Range Imaging Based on Smart Pixel Structures,” IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 55, no. 6, 2008.
[28] M. Perenzoni, N. Massari, D. Stoppa, L. Pancheri, M. Malfatti, and L. Gonzo, “A 160×120-Pixels Range Camera with In-Pixel Correlated Double Sampling and Fixed-Pattern Noise Correction,” IEEE Journal of Solid-State Circuits, vol. 46, no. 7, pp. 1672-1681, 2011.
[29] M. Davidovic, M. Hofbauer, K. Schneider-Hornstein, and H. Zimmermann, “High Dynamic Range Background Light Suppression for a TOF Distance Measurement Sensor in 180nm CMOS,” IEEE Sensors, pp. 359-362, 2011.
[30] M. Davidovic, M. Hofbauer, and H. Zimmermann, “A 33 × 25 µm² Low-Power Range Finder,” IEEE International Symposium on Circuits and Systems, 2012.
[31] C. Anand, V. K. Jacob, and M. Sarkar, “A Current Mode Time-of-Flight Pixel with 400 klx Background Light Subtraction,” IEEE International Midwest Symposium on Circuits and Systems, 2016.
[32] T. Liao, N.-A. Lee, and C.-C. Hsieh, “A CMOS Time of Flight (TOF) Depth Image Sensor with In-Pixel Background Cancellation and Sensitivity Improvement Using Phase Shifting Readout Technique,” IEEE Asian Solid-State Circuits Conference, 2017.
[33] T.-H. Hsu, T. Liao, N.-A. Lee, and C.-C. Hsieh, “A CMOS Time-of-Flight Depth Image Sensor With In-Pixel Background Light Cancellation and Phase Shifting Readout Technique,” IEEE Journal of Solid-State Circuits, vol. 53, no. 10, pp. 2898-2905, 2018.
[34] D. A. Kerth, “Switched-capacitor integrator with chopper stabilization performed at the sampling rate,” U.S. Patent 5,477,481, Dec. 1995.
[35] C. C. Enz and G. C. Temes, “Circuit Techniques for Reducing the Effects of Op-amp Imperfections: Autozeroing, Correlated Double Sampling, and Chopper Stabilization,” Proceedings of the IEEE, vol. 84, no. 11, pp. 1584-1614, 1996.
[36] J. F. Witte, K. A. A. Makinwa, and J. H. Huijsing, “A CMOS Chopper Offset-Stabilized Opamp,” IEEE Journal of Solid-State Circuits, vol. 42, no. 7, pp. 1529-1535, 2007.
[37] H. M. Jafari and R. Genov, “Chopper-Stabilized Bidirectional Current Acquisition Circuits for Electrochemical Amperometric Biosensors,” IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 60, no. 5, pp. 1149-1157, 2013.
[38] Q. Fan, K. A. A. Makinwa, and J. H. Huijsing, “Capacitively-Coupled Chopper Amplifiers,” Analog Circuits and Signal Processing, Springer, 2017.
[39] W.-F. Chou, S.-F. Yeh, and C.-C. Hsieh, “A 143dB 1.96% FPN Linear-Logarithmic CMOS Image Sensor with Threshold-Voltage Cancellation and Tunable Linear Range,” IEEE Sensors, 2012.